This invention relates generally to fluid testing apparatus and methods and more particularly, but not by way of limitation, to a device for imparting rotary motion to an object inside a pressure vessel.
In various industries there is the need for equipment and methods for testing fluids where some mixing or motion needs to be imparted to or within the fluid. For example, in the oil and gas industry, a fracturing fluid proposed to be used in a well bore to fracture a hydrocarbon-containing formation may need to be tested in a well-known device called a stirring autoclave. The fluid to be tested, comprising a mixture of substances, is introduced into the autoclave and then stirred to insure adequate mixing. Frequently, heat and pressure are then applied to simulate conditions in the well bore where the fluid is proposed to be used. Viscometers and consistometers are other examples in the oil and gas industry where a member or element inside a test chamber may need to be rotated to impart mixing or motion within the fluid. One technique for obtaining this motion is through a magnetic coupling/motor/endless belt assembly.
Although these types of equipment, such as the stirring autoclave, viscometer and consisoometer devices referred to above, have been known and used for a long time, we believe there is the need for an improvement in such equipment, namely, the improvement whereby the internal movable member is directly driven by, preferably, a stepper motor. Such an improvement should provide a relatively compact driving assembly. It should also provide highly accurate speed control of the movable member. This improvement should provide a more economical device, such as by replacing the aforementioned magnetic coupling/motor/endless belt assembly with a stepper motor.